Method of making an electrical circuit



April 16,1968 A. R. ElCK ETAL 3,377,598

METHOD OF MAKING AN ELECTRICAL CIRCUIT Filed Sept. 21. 1964 IN VE N TOHS fllber} 53 510k, [He/v11: J Racine, & Yunnan U Lazzx/ess ATTORNEY United States Patent M 3,377,698 METHOD OF MAKING AN ELECTRICAL CIRCUIT Albert R. Eick, Grand Blanc, and Melvin J. Racine and Norman D. Lawless, Flint, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Sept. 21, 1964, Ser. No. 397,846 1 Claim. (Cl. 29-625) This invention relates to preformed electrical circuits and the method of making the same and more particularly to the method of making preformed electrical circuits of relatively high current carrying capacity.

50 called printed circuits have gained wide acceptance in the electrical and electronic industries because they are compact, of light weight, easily duplicated and more economical than corresponding manually assembled circuits. Many electrical components, however, require considerably more current than can be handled by conventional printed circuits. The manufacture of high current carrying printed circuits by conventional methods such as etching or die cutting has proven dithcult and costly.

The present invention provides a method of producing a novel preformed electrical circuit assembly of relatively high current carrying capacity by automatically forming a bare copper wire, coining the ends of the wire to form terminals and encapsulating the wire between two layers of insulating material. In accordance with the present invention, there are no copper scrap costs and the overall circuits can be made more compact by using round wire rather than wide flat strips of conductive material.

A more complete understanding of the present invention can be had from the following detailed description which should be read in conjunction with the drawings in which:

FIGURE 1 discloses the apparatus utilized in making the circuit assembly;

FIGURE 2 is an enlarged view of a portion of the press shown in FIGURE 1;

FIGURE 3 is a plan view of the electrical circuit assembly.

FIGURE 4 is an exploded view of the circuit assembly;

FIGURE 5 is a side elevation view of the circuit assembly: and

FIGURE 6 is a sectional view along lines 6-6 of FIGURE 2.

Referring now to the drawings and initially to FIGURE 1, there is shown a press generally designated 10 including a ram 12 and a press bolster 14. The ram 12 is adapted for vertical reciprocation and carries a punch holder 16, a cut on blade 18, a coining punch 26, and a pressure pad 22. The ram 12 also carries a rubber punch holder 24 and a rubber punch 26 and is adapted to move horizontally in the punch slide 23. The rubber punch 26 is provided with openings 29 to which a source of vacuum may be attached for purposes which will be apparent hereinafter.

The press bolster -14 supports a horizontally movable slide 30 which supports a die holder 32. The die holder 32 supports coining dies 34 and a stripper pad 36 which is slightly biased away from the holder 32 by a plurality of springs such as shown at 37. The stripper pad 36 includes openings 38 registering with the coining dies 34 and is also provided with a plurality of grooves 40. The pressure pad 22 cooperates with the grooves 40 to provide passageways 44 for the reception of flexible wires 46. The slide 30 also supports a retaining die 48 spaced from the die holder 32 and adapted to register with the punch 26.

The flexible wires 46 emanate from a source (not shown) and pass through guide tubes 49 feed rolls 50,

3,377,698 Patented Apr. 16, 1968 and a guide block 52 having suitably dimensioned openings 53 therein for reception and guiding of the wires 46.

The method of making the electrical circuit assembly shown in FIGURE 3 is as follows. The ram 12 is lowered to a partially closed position, as best shown in FIGURE 2, where the pressure pad 22 and the die stripper pad 36 form the passageways 44. The wires 46 are then fed through the openings 53 in the guide block 52 and into the passageways 44. As the wires are pushed through the passageways 44, they conform to the desired circuit configuration as determined by the grooves in the stripper pad 36 and the pressure pad 22. Upon reaching the ends of the passageways 44, slip clutches on each of the wire feed rolls stall out thus stopping the infeed of each wire. After all the wires 46 have been fed in place, the ram 12 is further lowered, cutting off the feed end of the wires and coining the ends of the wires in the desired shape for circuit connections.

The ram 12 is now raised to a fully opened position and the die holder 32 is moved to the left on the slide 30 to a position beneath the rubber punch 26. A preblanked pressure sensitive mylar sheet 54 is placed in location on the rubber punch 26 and is held in position by vacuum applied through the openings 29. The protective paper on the pressure sensitive mylar sheet 54 is peeled off to expose an adhesive coating and the ram 12 is lowered bonding the preformed and coined copper wires 46 to the pressure sensitive mylar sheet 54. The ram 12 is then raised retaining the mylar sheet 54 and the wires 46 arranged in the desired circuit configuration on the rubber punch 26.

A preblanked base mylar sheet 58 is suitably placed in location on the retaining die 48 and the slide 30 is moved rightwardly so that the die holder 32 is once again under the pressure pad 22 and the retaining die 48 is directly below the rubber punch 26. As the ram '12 is lowered to begin another sequence of operation, the rubber punch 26 presses the pressure sensitive mylar sheet 54 to the base mylar sheet 58 bonding them together and encasing the preformed and coined copper wires 46. Preferably, the circuit assembly may then be subjected to a heating operation to insure complete bonding and curing.

The finished product is shown in FIGURES 3, 4 and 5 and it will be noted that the coined ends 60 of the copper wires 46 extend beyond the mylar sheets 54 and 58 and that the mylar sheet 54 is provided with openings 62 which correspond to the openings 38 in the stripper pad 36 so as to register with the coined ends 64 of the Wires 46. Thus, the wires 46 are insulated from each other and yet are readily adaptable for electrical connection to circuit components.

While only one preferred product and process of this invention has been illustrated and described, it is obvious that those skilled in the art may make changes thereto without departing from the spirit and scope of this invention.

We claim:

1. The method of making an electrical circuit assembly comprising the steps of defining a desired circuit configuration through the cooperation of two parts of a fixture having grooves in at least one of said parts to form passageways terminating at one end and having entrance openings at the other end, feeding a plurality of flexible electrically conductive wires through said entrance openings into said passageways to the terminating end thereof whereby each of the wires con-forms to the shape of the respective passageways, severing the wires at a desired length and coining the opposite ends of the wires in a desired shape for circuit connections, moving one of said parts relative to the other part to expose a portion of said wires with the unexposed portion of said wires remaining in the grooves of said other part, placing a first sheet of insulating material having a pressure sensitive adhesive coating on .one side thereof in contact with the exposed portion of said Wires, applying pressure to said sheet sufiicient to activate said coating and adhere said Wires to said sheet, pulling said sheet relative to said other part to remove said wires frern said. grooves and expose said remaining portion of said Wires, placing a second sheet of insulating material having a pressure sensitive adhesive coating on one side thereof in contact with the remaining portion of said wires, to encase said wires with said opposite ends being exposed.

References Cited UNITED STATES PATENTS 2,613,252 10/1952 Heibel -2 29-1555 10/1960 Wintriss 29-15555 3/1963 Francis et a1 174-88 9/1964 Gray 317-101 11/1964 De Mase 174-685 2/1965 Sc-rvillo 339-17 X 6/1965 Johnson 29-1555 5/1965 Strohel a- 339-17 5/1964 Seele 264-261 3/1966 Love 29-1555 FOREEGN iATENTS 3/1960 Canada.

JOHN F. CAMPBELL, Primary Examiner. 15 R. W. CHURCH, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Pate-wt NO 3,377 ,698 April 16 1968 Albert R. Eick et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 5, "Sorvil1o---339l7X" should read H Richter----l74117 line 6, "Johns0n---29-l55.5" should read Sorvi11o--- -339-17E XR line 7 "Strobe1- *339-17" should read Johnson-1S5.S

Signed and sealed this 9th day' of September 1969.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer WILLIAM E. SCHUYLER, JR. 

1. THE METHOD OF MAKING AN ELECTRICAL CIRCUIT ASSEMBLY COMPRISING THE STEPS OF DEFINING A DESIRED CIRCUIT CONFIGURATION THROUGH THE COOPERATION OF TWO PARTS OF A FIXTURE HAVING GROOVES IN AT LEAST ONE OF SAID PARTS TO FORM PASSAGEWAYS TERMINATING AT ONE END AND HAVING ENTRANCE OPENINGS AT THE OTHER END, FEEDING A PLURALITY OF FLEXIBLE ELECTRICALLY CONDUCTIVE WIRES THROUGH SAID ENTRANCE OPENINGS INTO SAID PASSAGEWAYS TO THE TERMINATING END THEREOF WHEREBY EACH OF THE WIRES CONFORMS TO THE SHAPE OF THE RESPECTIVE PASSAGEWAYS, SEVERING THE WIRES AT A DESIRED LENGTH AND COINING THE OPPOSITE ENDS OF THE WIRES IN A DESIRED SHAPE FOR CIRCUIT CONNECTIONS, MOVING ONE OF SAID PARTS RELATIVE TO THE OTHER PART TO EXPOSE A PORTION OF SAID WIRES WITH THE UNEXPOSED PORTION OF SAID WIRES REMAINING IN THE GROOVES OF SAID OTHER PART, PLACING A FIRST SHEET OF INSULATING MATERIAL HAVING A PRESSURE SENSITIVE ADHESIVE COATING ON ONE SIDE THEREOF IN CONTACT WITH THE EXPOSED PORTION OF SAID WIRES, APPLYING PRESSURE TO SAID SHEET SUFFICIENT TO ACTIVATE SAID COATING AND ADHERE SAID WIRES TO SAID SHEET, PULLING SAID SHEET RELATIVE TO SAID OTHER PART TO REMOVE SAID WIRES FROM SAID GROOVES AND EXPOSE SAID REMAINING PORTION OF SAID WIRES, PLACING A SECOND SHEET OF INSULATING MATERIAL HAVING A PRESSURE SENSITIVE ADHESIVE COATING ON ONE SIDE THEREOF IN CONTACT WITH THE REMAINING PORTION OF SAID WIRES, TO ENCASE SAID WIRES WITH SAID OPPOSITE ENDS BEING EXPOSED. 